Field of the Invention
This invention relates to a process for producing L-aspartyl-L-phenylalanine methyl ester (abbreviated as APM hereinafter) or L-aspartyl-L-phenylalanine (abbreviated as AP hereinafter).
Description of the Prior Art
APM is a peptide which is noted as a sweetener in recent years.
It is well-known that the processes for the production of APM or AP include a chemical synthesizing process and an enzymatic synthesizing process.
The chemical synthesizing process for the production of APM comprises condensing N-protected L-aspartic acid anhydride and L-phenylalanine methyl ester (abbreviated as PM hereinafter) to obtain N-protected APM and then removing the protective group afterwards. The enzymatic synthesizing process comprises exerting the effect of a protein-decomposing enzyme on N-protected L-aspartic acid and PM to obtain N-protected APM or the PM adduct of N-protected APM and then removing the protective group to form APM. However, both processes require the complicated steps of introducing the protective groups and removing the same.
There is also known a process for producing APM without using the protective groups (Japanese Patent Kokai No. 43793/1983, "Digests of the Publications at the Annual Meeting of the Agricultural Chemical Society of Japan" in 1983, p. 42) which is a microbiological synthetic process using one of Pseudomonas, Torulopsis, Rhodotorula, and Sporobolomyces, but this is not always suitable for the industrial production of APM because of the extremely low yields.